Web forming apparatus

ABSTRACT

An apparatus for forming an air-laid non-woven web wherein a pair of parallel lickerins are positioned adjacent one another with the lickerins being rotated in opposite directions, so that when a first supply of fibrous material is fed to one lickerin and a second supply of fibrous material is fed to the other lickerin, separate supplies of individualized fibers are produced that are entrained in separate air streams impelled toward one another and toward a mixing zone between the lickerins. The individualized fibers are doffed from lickerins by the separate air streams and centrifugal force, and the doffed fibers are given an initial trajectory, whereby the inertia of the fibers is sufficient to allow at least a portion of the fibers from each supply to become homogeneously blended as the air streams are impelled against one another. A suction actuated fiber condensing means is positioned in communication with the mixing zone, and the separate air streams are combined into a common air stream that directs the fibers through the mixing zone and toward the condensing means where the fibers are deposited to produce a web comprised of randomly oriented fibers. When the material fed to the first lickerin includes relatively long fibers, such as textile length fibers, and the material fed to the second lickerin contains relatively short fibers, such as papermaking fibers, a web of randomly arranged fibers can be produced having a dispersion of different length fibers in more or less uniform intermixtures, to create a web having desired properties.

United States Patent [1 1 Lovgren Nov. 20, 1973 [73] Assignee: Johnson &Johnson, New

Brunswick, NJ.

[22] Filed: Jan. 21, 1971 [21] Appl. No.: 108,547

Ernest G. Lovgren, Palos Park, Ill.

[52] U.S. Cl. 19/156.3 [51] Int. Cl D0lg 25/00 [58] Field of Search19/155, 156, 156.4, 19/205, 88, 89, 105

[5 6] References Cited UNITED STATES PATENTS 1,810,675 6/1931 Nuttall etal 19/89 X 2,150,040 3/1939 Seigle et al. 19/155 X 2,451,915 10/1948.Buresh 19/105 X 2,911,684 11/1959 Hunter 19/205 X 3,052,928 9/1962Charlton, Jr. et al.. l9/156.3 3,512,218 5/1970 Langdon 19/156 33,535,187 10/1970 Wood 19/156.4 UX 3,579,744 5/1971 Menzies, .Ir.....19/105 FOREIGN PATENTS OR APPLICATIONS 545,638 6/1942 Great Britain19/89 Primary Examiner-Dorsey Newton Att0rney-Michael Q. Tatlow, HarolwL. Warner and Robert L. Minier [57] ABSTRACT An apparatus for forming anair-laid non-woven web wherein a pair of parallel lickerins arepositioned adjacent one another with the lickerins being rotated inopposite directions, so that when a first supply of iibrous material isfed to one lickerin and a second supply of fibrous material is fed tothe other lickerin, separate supplies of individualized fibers areproduced that are entrained in separate air streams impelled toward oneanother and toward a mixing zone between the lickerins. Theindividualized fibers are doffed from lickerins by the separate airstreams and centrifugal force, and the doffed fibers are given aninitial trajectory, whereby the inertia of the fibers is sufficient toallow at least a portion of the fibers from each supply to becomehomogeneously blended as the air streams are impelled against oneanother. A suction actuated fiber condensing means is positioned incommunication with the mixing zone, and the separate air streams arecombined into a common air stream that directs the fibers through themixing zone and toward the condensing means where the fibers aredeposited to produce a web comprised of randomly oriented fibers. Whenthe material fed to the first lickerin includes relatively long fibers,such as textile length fibers, and the material fed to the secondlickerin contains relatively short fibers, such as papermaking fibers, aweb of randomly arranged fibers can be produced having a dispersion ofdifferent length fibers in more or less uniform intermixtnres, to createa web having desired properties.

8 Claims, 24 Drawing Figures United States Patent [1 1 [111 3,772,739

Lovgren [451 Nov. 20, 1973 PATENIEU Nov 20 I975 sum 8 CF 8 1 WEB FORMINGAPPARATUS This invention relates generally to air-laid nonwovenmaterials, and more particularly to air-laid monwoven webs consisting ofa more or less uniform intermixture of randomly oriented fibers.Preferably, the web comprises a substantially homogeneous blend of longand short fibers; i.e., textile length and papermaking fibers.

Fibers are usually classified according to length, with relatively longor textile length fibers being longer than about one-fourth inch andgenerally between one-half and two and one-half inches in length. Theterm long fibers as used herein, refers to textile fibers having alength greater than one-fourth inch, and the fibers may be of natural orsynthetic origin. The term short fibers," as used herein, refers topapermaking fibers, such as wood pulp fibers or cotton linters having alength less than about one-fourth inch. While it is recoghized thatshort fibers are usually substantially less costly than long fibers, itis also recognized in many instances that it is desirable to strengthena short fiber product by including a blend of long fibers therein.

In the recent past, nonwoven fabrics have met with increasing commercialacceptance because such fabrics can be made with physical properties,and appearance, more or less comparable with the more expensive wovenfabrics. In general, these fabrics are structures consisting of a randomassemblage or web of fibers which are joined together with a binder toprovide the desired strength.

It is well known to produce nonwoven webs of textile length fibers by aconventional carding process, and this results in an anisotropic webwherein the fibers are aligned predominantly in the machine direction.It is also known to produce a nonwoven web by a garnetting process, andwhile webs produced by this technique have less fiber orientation thancarded webs, the garnetted webs are generally of unsatisfactoryuniformity and also are limited to textile length fibers. Furthermore,the rate at which webs can be produced by either of these techniques islimited, and these techniques do not lend themselves for use in makingthe very low cost nonwoven fabrics, especially those embodying the use vof the relatively low cost wood pulp fibers.

It is also known to eliminate directionality in carded or garnetted websby replacing the doffing cylinder used in these processes with an airduct leading to an air condenser. in one arrangement, known as theDuo-Form technique, a carding lickerin individualizes fibers frompre-opened textile length stock, and an intermediate doffing andtransfer cylinder feeds the opened fibers to a second lickerin forfurther opening. The fibers removed from the second lickerin are carriedby an air stream and deposited on a screen cage where the web is formed.The Duo-Form process is limitedto the production of a web having textilelength fibers, and the successful operation of the process requiresthorough pre-opening of the fibrous stock.

Another machine that has been proposed for eliminating directionality incarded or garnetted webs consists of two traveling flat cards havingdoffers which confront one another. Rapidly rotating needle cylindersremove the fibers from the card doffers and transport them in anessentially inverted .l-shaped path through the converging upperbranches of a generally Y-shaped duct system. The lower branch of theduct system is traversed by a horizontally moving screen upon which thefibers are condensed. This latter apparatus is, of course, limited totextile length materials, and even though the output of two cards iscombined, the total production rate is still unsatisfactory.

The velocities of the air streams flowing through the convergingbranches of the generally Y-shaped duct system of the machine justreferred to is, of necessity, quite limited. These low velocities arerequired to avoid upsetting the web on the doffing cylinders of thecards prior to removal of the fibers by the rotating needle cylinders.Also, while this machine ultimately combines the output of two cardsinto a single duct, because of the necessity of having low airvelocities and thus eliminating the possibility of turbulent flowconditions, in the event that two different textile length fibers werefed into the converging branches of the duct system of the machine,little or no blending of the different fibers would take place, andinstead a web of an essentially laminar arrangement of fibers wouldresult with a marked interface between the layers of fibers.

Nonwoven webs have also been produced by feeding filamentary materialdownwardly between oppositely rotating beater blades which break up orrupture the filaments to form long fibers as the filaments are fedbetween the beater blades. The thus formed fibers are subsequentlydeposited on a screen or other condenser to form a web, and while suchwebs may have the textile length fibers randomly arranged, the processis limited to use with tow or other continuous filament material as thesource of the fibers.

A further process for producing a random web of textile length fibers isknown as the Rando-Webber process, and is practiced upon apparatusavailable from the Curlator Corporation of East Rochester, New York. Inthis process, pre-opened textile length fibrous material is fed to asupply device, which further opens and delivers the fibrous material asa loose mat to a web forming unit. The mat is compressed and fed over anose bar where it is brought into contact with a lickerin, and the teethof the lickerin remove fibers from the mat and introduce them into ahigh velocity, low pressure air stream in the reduced cross sectionthroat of a duct. The fibers are subsequently deposited in randomfashion on a condensing screen to produce a substantially isotropic web.While this process and apparatus have functioned generallystaisfactorily to produce a relatively uniform random web of textilelength fibers, it is generally not suitable for use with short fibersnor with blends of short and long fibers. Furthermore, throughputs withthis type of apparatus are limited.

It has recently been proposed to produce a random fiber web consistingentirely of short fibers, and one such process is known as the Texpaprocess that is practiced upon apparatus also available from theCurlator Corporation of East Rochester, New York. This apparatusconsists essentially of two adjacent, generally vertically disposedforaminous belts that converge downwardly and that are positioned incommunication with a duct carrying short fibers. A pair of oppositelyrotating opening cylinders are positioned in close adjacency to oneanother beneath the converging belts, and a suction actuated fibercondensing means is positioned below the opening cylinders. Suction isapplied to the foraminous belts to withdraw fibers from the conveyingduct thereabove, and the belts convey the fibers downwardly where theyare compressed into a single mat at the point of convergence of the twobelts. The single mat is fed downwardly to the opening cylinders, one ofwhich is rotating at a faster speed than the other. The cylinders haveoppositely disposed teeth, so that as the mat is fed downwardly betweenthe cylinders, the downwardly facing teeth of one cylinder carry thefiber through the nip between the cylinders, while the upward facingteeth of the other cylinder hold the fibers back. This action tears themat into individual fibers which are then carried by an air stream ontoa condenser belt to form a random web. The Texpa" process is generallynot suitable for use with long fibers, or blends of long and shortfibers, and the throughputs obtained with this process are limited.

The desirability of, and need for, a web comprised of a mixture of longand short fibers is well understood by those skilled in the art. Ingeneral, the desired characteristics of the nonwoven end product as wellas its utility dictate the type of fibers and the relative proportionsof long and short fibers to be used. Thus, for example, the product mayrequire one or more characteristics such as tear resistance, abrasionresistance, washability and stretchability, burst strength, absorptionor nonabsorption to different liquids, heat sealability, ability toresist delamination, etc., all of which will influence the type of fiberor mixture of fibers to be used. Thus, by way of specific example,absorbent products requiring strength characteristics may be acombination of two or more different fibers such as wood pulp fibers andrayon or similar fibers in varying percentages.

Likewise, again depending on the nature of the product desired, theproduct may have to possess substantially random characteristics asopposed to oriented fiber characteristics in order to provide forbalanced properties in both the machine and cross direction for mostuses. For example, in the case of products intended for surgical orsimilar uses requiring absorbency characteristics, such as a sanitarynapkin or a portion thereof, absorbent surgical drapes, etc., mixturesof randomly oriented short and long fibers are required to provideimproved mechanical characteristics; while in the case of nonwovenmaterials suitable for use as disposable items in the field of diapers,short fibers are generally employed.

Typical of the short fibers are wood pulp fibers from various types ofwoods, cotton linters, asbestos fibers, glass fibers and the like; withwood pulp fibers being those which find most frequent use in a largevariety of products due to their ready availability and economicalattributes. Typical of the long or staple length fibers are syntheticfibers such as cellulose acetate fibers, vinyl chloride-vinyl acetatefibers (e.g. the product marketed under the trademark VINYON), polyamidefibers such as NYLON 6, NYLON 66, etc., viscose staple rayon,cupra-ammonium rayon or other regenerated cellulose fibers includingsaponified ester fibers, cellulose ester fibers such as celluloseacetate and cellulose triacetate, acrylic fibers, polyester fibers,polyvinyl chloride fibers, polyolefin fibers such as polyethylene andpolypropylene, fluorocarbon fibers such as TEF- LON" and natural fiberssuch as cotton, flax, jute, wool, silk, ramie or rag, or protein fiberssuch as VlCARA Combinations of any of the short and staple or longfibers may be employed in this invention. The denier of the fibers usedmay vary over a wide range and may be from one-half to 100 depending onthe type of fiber employed and the requirements of the nonwovenmaterial. Commonly, when using staple fibers such as rayon, the denierwill vary from 0.75 to 5 or 6 denier.

Conventionally, the shorter type of fibers such as wood pulp fibers arecommerically available for airlaying processes in the form of pulpboards, which are compressed sheets of fibers in intimate contact witheach other. The pulp boards come in varying thicknesses and lengths,typical thicknesses being from onesixteenth of an inch tothree-sixteenths of an inch, and sometimes more. If desired, thestarting material such as pulp boards may be comprised of a mixture oftwo or more different fibers, preferably of approximately the samelength. Thus, by way of example, in place of utilizing a conventionalwood pulp board, a board may be of a mixture of wood pulp fibers andcotton linters, asbestos fibers, glass fibers, etc. Thus, differentproperties may be imparted to the product by employing variouscombinations of fibers.

In the case of staple or longer length fibers, such as rayon, forexample, they are normally commerically available in bale form invarious fiber lengths; and for use in the present invention, they aregenerally employed in a pre-opened oriented condition, termed a cardedweb or carded batt in the art. To this end, baled rayon can be formedinto a carded lap according to conventional techniques known to thoseskilled in the art, which, briefly summarized, first involves form ationof a picker lap wherein the fibers are formed into a uniform batt ofgenerally constant weight, whereafter they are carded to orient and openand comb the fibers, and thus form the carded batt. If desired, in placeof using a carded batt of only rayon, a mixture of rayon and other fiberor fibers, or for that matter a mixture of any two or more differentlong fibers can be employed, thereby providing a product havingdifferent fibers and with them the different properties they impart tothe ultimate nonwoven fabric. It is not necessary that the staple lengthfibers be used in the form of a carded batt but these fibers may bepresented to the machine of the present invention by other means wellknown to those skilled in the art, such as chute feeding, CMC even feed,or directly from a card, for example.

Those skilled in the art have recognized the long felt need forproviding a process and apparatus for producing a web of homogeneouslyblended short and long fibers, as described above, with substantiallyall of the fibers being randomly disposed. Various systems have beenproposed in the past, but none have met with wide commercial successbecause of the failure to either get satisfactory randomnization,satisfactoy homogenization, or a satisfactory production rate.

For example, it has been proposed to individualize short fibers by amilling device, such as a hammer mill or a fitz mill, and to entrain theindividualized short fibers in an air stream into which individualizedlong fibers are fed. In one known technique, the individualized shortfibers are transported in a horizontal duct, with a lickerin rotating ata narrowed throat portion of the duct and combing individual fibers froma long fiber web or mat and introducing them into the short fiber airstream traveling therebelow. It has been proposed to form a web bydepositing the airborne fibers on a foraminous condenser that intersectsthe duct, or by allowing the duct to feed fibers into a gravity settlingbox, where they settle by gravity on a foraminous conveyor. In eithertechnique, because the long fibers are introduced into the air streamabove the short fibers, the resulting webs have a tendency towardstratification, with the long fibers predominating at the top of theweb, and the short fibers predominating at the bottom of the web. Thislack of complete homoginization has made such processes generallyunsatisfactory.

Webs of blended short and long fibers that have been produced by suchprior art techniques have not only exhibited a marked different inproperties from one side to the other, but also have shown a definitetendency to strip or separate at the line of demarcation between thelayers. While such webs have been satisfactory for certain products,particularly where the web is an internal layer that is not visible tothe consumer, such webs have not been completely satisfactory for otherproducts, particularly where strength is required and, also, where theweb is exposed to view by the consumer.

One of the major problems in connection with blended fibrous webs formedby prior art techniques is in the proper opening of the fibrousmaterials at high speeds to substantially completely individualize thefibers without damaging them. For example, a single lickerin has beenused to simultaneously open both long and short fiber materials, and ithas been found that lickerin speeds that are suitable to open the shortfiber material in a high speed commercial operation have causedexcessive damage to the fibers of the long fiber material.

In webs produced by prior art techniques, it is common to find arelatively large percentage of incompletely opened clumps of fibers andit is also common to find a relatively large percentage of salt likehardened particles that are formed by compressing individual fibersduring the fiberizing step. Such webs have not been visually acceptableand suitable for use as an exposed layer in an end product, since theyare not uniform in appearance. Furthermore, in webs having clumps offibers, or hardened particles of broken and/or compacted fibers, thefunctional characteristics of the web are not uniform. For example, thepresence of clumps of fibers or compacted fibers causes the web to be ofvariable weight, strength, cohesiveness, fluid absorbtiveness and unevenin color when dye is used. Webs having a high percentage of salt-likeparticles, are completely unsatisfactory for many uses, such as surgicaltowels and dressings, because of the tendency of these particles toflake off the web.

To obviate such problems, it has been necessary to rotate the lickerinat a compromise speed, which is not suitable for commercial production.Other techniques that have been proposed in the past have the same orsimilar problems.

In accordance with the process and apparatus of the present invention, anonwoven web of substantially completely open fibers, preferablyrandomly oriented, is produced wherein at least a portion of the webconsists of a homogeneous blend of fibers from two separate and distinctsupplies of fibers. The present invention utilizes a pair of parallellickerins that are rotated in opposite directions to individualizefibers from each supply. When the web is to include a blend of long andshort fibers, the lickerin for the short fibers is rotated at a fasterspeed than the lickerin for the long fibers. A backing member isprovided for each fibrous source adjacent its respective lickerin, anddifferent and optimum opening relationships may be established betweeneach lickerin and the nose bar portion of its associated backing member.

The fibers are doffed from the lickerins substantially immediately afterindividualization by separate gaseous streams flowing adjacent eachlickerin, and by centrifugal force, which tends to throw the fibers intotheir respective gaseous streams. The supplies of indivualized fibersare entrained in the separate gaseous streams, and the streams areimpelled toward one another and toward a generally centrally disposedmixing zone, where the fibers intermix.

The supplies of individualized fibers are combined in a common gaseousstream flowing downwardly through the mixing zone, in an exemplary formof the invention. The common air stream may be produced by thecooperative action of a suction actuated fiber condensing means at theterminal end of the mixing zone and by the air generated by the rotaryaction of the oppositely rotating lickerins.

In the process of the present invention, the fibers entrained in theseparate gaseous streams have a trajectory including a componentdirected toward one another, as well as a component directed toward themixing zone. Although the fibers are transported by the separate gaseousstreams through the mixing zone, the fibers have sufficient kineticenergy by virtue of their mass and velocity that the fibers continue totravel generally in the direction of their initial trajectory because oftheir inertia. The component of motion of the fibers toward one anothercauses them to combine in an intimate mixture of fibers as the gaseousstreams are impelled against one another and combined into thecommon'stream. The combined stream transport the mixed and blendedfibers through the mixing zone to a condensing means where the fibersare deposited to build up a web of the desired thickness.

The blending action may be regulated by controlling certain machineparameters, such as the rate of fiber input, the volume and/or velocityof the air flowing through the machine, the speeds of the lickerins,type of lickerin teeth and the winding of the clothing, and the geometryof the ducting system. For example, at relatively low air volumes, whenproducing a web comprised of homogeneously blended short and longfibers, since the short fiber lickerin is rotating at a higher speedthan the long fiber lickerin, a differential velocity is created in thecommon gaseous stream, with the portion of the gaseous stream on theshort fiber side of the machine having a greater velocity (and hence alower pressure) than the portion of the gaseous stream on the long fiberside of the machine. Therefore, the individualized long fibers areaccelerated and drawn into the faster moving zone of air, and theacceleration of the individualized long fibers keeps them under tensionsubstantially until they are deposited on the fiber condensing means.The suction or drawing action created by the faster rotating short fiberlickerin enhances the intimate admixure of the long fibers with theindividualized short fibers.

Also, by having relatively higher gas volumes, with an appropriatelyshaped ducting system, the gas passing through the machine can beretained in a turbulent condition, which also enhances the degree ofblending of the long and short fibers.

In one embodiment of the invention a variable nose bar-lickerinrelationship is provided for each supply of fibrous material, so thatthese realtionships can be individually adjusted and controlled fordifferent materials to produce a lickerin action that will substantiallycompletely open the respective fibrous materials.

The relationship of the fiber condensing means to the fiber mixing zoneis also adjustable in an illustrative embodiment of the invention, sothat by establishing a desired relationship between the mixing zone andcondensing means, the directioning of the individual fibers of theresulting web can be varied and controlled between a completelyrandomized orientation, and an orientation wherein a majority of thefibers extend either lengthwise or crosswise of the web.

The process and apparatus of the present invention produces a web havingat least a portion comprised of a homogeneous admixture of long andshort fibers; and in webs where all of the fibers are homogeneouslyblended, such webs are not only uniform in external appearance, but alsohave uniform functional characteristics including weight, thickness,etc.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view, partlyin section, of a web forming apparatus constructed in accordance withthe present invention;

FIG. 2 is a side elevational view, partly in section and partly brokenaway, of the apparatus illustrated in FIG.

FIG. 3 is an enlarged sectional view taken generally along line 33 ofFIG. 2;

FIGS. 4l2 are enlarged, fragmentary sectional views of modifiedconfigurations for the mixing zone of the apparatus illustrated in FIGS.13;

FIG. 13 is a central sectional view through a further embodiment of theweb forming apparatus, and FIG. 13 is taken generally along line l313 ofFIG. 14;

FIG. 14 is a front elevational view of the apparatus illustrated in FIG.13;

FIG. 15 is a fragmentary perspective view illustrating details of thecondensing screen of the embodiment of FIGS. 13 and 14;

FIG. 16 is an enlarged sectional view taken generally along line 16-16of FIG. 15;

FIGS. 17-19 are schematic representations of the apparatus illustratedin FIGS. 13-16, and illustrate the baffle in different positions;

FIGS. 20-23 illustrate in cross section various webs that can beproduced by the apparatus of FIGS. 13-16 and FIG. 24 is an enlargedschematic view illustrating the profile of the lickerin teeth used inthe apparatus of the present invention.

DETAILED DESCRIPTION OF THE INVENTION While this invention issusceptible of embodiment in many different forms, there is shown in thedrawings and will herein be described in detail only preferredembodiments of the invention and modifications thereof, with theunderstanding that the present invention is to be considered as anexemplification of the principles of the invention and is not intendedto limit the invention to the embodiments illustrated. The scope of theinvention will be pointed out in the appended claims.

Referring now to the drawings in detail, and particularly to FIGS. 1-3,an exemplary embodiment of the apparatus of the present invention isindicated generally at 20, and the apparatus 20 includes frame means 22supporting first and second fiberizing means 24 and 26 adjacent theupper end thereof, and supporting a suction actuated fiber receivingmeans 28 therebelow, as will hereinafter be described in detail.Fiberizing means 24 and 26 are operative on separate sources of fibrousmaterial to substantially completely open the material and createseparate supplies of individualized fibers that are entrained andconveyed in separate gaseous streams directed toward each other andtoward a common mixing zone 25 therebetween. The individual fibers aredoffed from the fiberizing means 24 and 26 by centrifugal force and bythe separate gaseous streams moving relative to the fiberizing means.The separate gaseous streams are impelled against one another, and arecombined into a common high speed gaseous stream flowing through themixing zone 25 toward the fiber receiving means 28. The fibers are givenan initial trajectory in the doffing direction, and the kinetic energyimparted to the fibers by virtue of their mass and velocity enables themto have substantial inertia and continue to have a significant componentof motion toward the other supply of fibers. This allows at least aportion of the fibers of each supply to become homogeneously blended andfurther mixing can take place in the mixing zone 25 by adjusting certainmachine conditions, as is hereafter explained. The entrained fibers arethen directed to, and deposited upon, receiving means 28 by the commonair stream to build up a web W. A doffing roll 27 is supported uponframe means 22 adjacent receiving means 28 for removing web W therefromand transferring it to a conveyor 29 therebelow.

The apparatus of the present invention includes frame means 22 definedin part by upright members 30 that are connected to one another by uppercrossrails 32 and lower crossrails 34. A subframe 36 is mounted uponupper crossrails 32, and subframe 36 includes a pair of spaced sideplates 38 that are stabilized by transversely extending tie rods 40.Fiberizing means 24 and 26 are supported between side plates 38 at firstand second fiberizing stations, respectively.

In order to be able to change the characteristics of web W, as byvarying the direction and pattern in which the individualized fibers aredeposited on the fiber receiving means 28, in the embodiment illustratedin FIGS. 1-3, the position of the fiber receiving means 28 relative tothe mixing zone 25 can be varied, and for this purpose, a pair oftransversely extending frame members 42 are adjustably connected touprights 30. A vertical adjustment means is provided by plates 44 thatare fixed to opposite ends of each frame member 42, with the plates 44each including spaced, vertical slots 46. Locking bolts 48 impale slots46 and are threaded into internally threaded openings in uprights 30, sothat the frame members 42 can be moved vertically when the locking bolts48 are loosened, and positively retained in the desired positionrelative to mixing zone 25 when locking bolts 48 are tightened.

Fiber receiving means 28 includes side plates 50 at opposite endsthereof, and horizontally or lateral adjustment of the fiber receivingmeans 28 is effected by mounting bolts 52 that are slidably mounted inelongate slots 54 in the upper flange 56 of frame member 42. As can beseen in FIG. 1, bolts 52 extend through openings in mounting feet 58that extend laterally from the lower ends of side plates 50, and nuts 60are threaded upon bolts 52 to retain the fiber receiving means 28 in thedesired position of lateral adjustment relative to mixing zone 25. Whilethe position of the fiber receiving means 28 is variable in theillustrated embodiment of the invention, it should be understood, thatthe adjustability feature is not critical to the present invention,when, in use, a given type of web is to be continuously produced on themachine.

A mass of long or textile length fibers 62 of the type described above,is fed to fiberizing means 24 by a cylindrical feed roll 64. Theopposite ends of feed roll 64 are rotatably supported upon mountingplates 38, and the feed roll 64 is positively rotated by conventionalmeans, not shown, to control the rate and amount of long fiber materialthat is fed to the fiberizing means 24.

The present invention includes adjustment means 66 for varying theposition of the feed roll 64 relative to a nose bar assembly 68 foraccommodating different thicknesses of long fiber material. Theadjustment means 66 includes a mounting block 70 adjacent each sideplate 38, and each block 70 is generally T-shaped in cross section withan offset portion being slidably mounted in an inclined slot 72 in theadjacent mounting plate 38. Each block 70 includes a recess 74 thatpositions a further mounting block 76 for movement perpendicularly toslots 72. Mounting blocks 76 include a boss 78 having the ends of thefeed roll 64 rotatably mounted therein, and elongate slots 80 at eachside of blocks 76 are impaled by clamping bolts 82 that are threadedinto blocks 70-to allow the blocks 76 to be adjusted at right angles toslots 72. In this manner, the clearance between the feed roll 64 andnose bar assembly 68 can be set at an optimum gap for the particulartype and thickness of the fibrous source 62.

Feed roll 64 is retained in a positive material feeding relationshipwith the nose bar assembly 68, and to this end, feed roll 64 is urgedtoward the nose bar assembly 68 by springs 84 that act between a recessin one end of each block 70 and an aligned recess in an abutment plate86 that is secured to each side plate 38. Elongate guide slots 88 areprovided in each corner of blocks 70, and clamping bolts 90 impale slots88 and are threaded into openings in side plates 38. The ends of slots88 limit the movement of feed roll 64 toward the nose bar assembly 68and provide a minimum clearance therebetween, it being understood thatthe bolts 90 can be .tightened to positively secure the feed roll 64 ina selected position of adjustment. By virtue of the abovedescribedadjustment means 66, it will be appreciated that feed roll 64 can belocated in any of a plurality of locations relative to the nose barassembly 68. However, in a situation where the fibrous source 62 willalways be substantially the same, it should be understood that theadjustment means 66 can be eliminated or greatly simplified.

In order to provide a first supply of individualized fibers, a materialopening cylinder 92 is mounted for rotation in a clockwise directionbetween side plates 38 below feed roll 64, and opening cylinder 92preferably takes the form of a lickerin having spirally wound toothedclothing 94 thereon. The teeth of the rayon lickerin usually have alower tooth height and pitch than the pulp lickerin. The pitch andheight of the teeth used on the lickerin for the rayon may vary, ggodresults being obtained with a tooth pitch of about oneeighth inch toabout one-fourth inch and a tooth height of about one-eighth inch toabout one-fourth inch. The

angle of the teeth of the lickerin for the rayon may also vary,generally within the limits of about -l0 to about The teeth 96 may haveonly a slight positive rake, or even a slight negative rake, tofacilitate doffing of the short fibers from the lickerin 92.

Adjustment means 98 is provided for varying the position of the nose barassembly 68 relative to the lickerin 92, so as to provide optimumconditions for substantially fully opening the long fiber material 62without damaging the fibers thereof. The nose bar assembly 68 includes aholder 100 that extends between side plates 38, and holder 100 supportsa nose bar 102 thereon that has a curved material supporting surfacefacing feed roll 64. Holder 100 is mounted for movement toward and awayfrom lickerin 92 in inclined slots 104 in side plates 38, and theposition of holder 100 is adjusted by screws 106 that are threaded intoholder 100, with screws 106 reacting against saddle members 108 that aresecured to side plates 38. A support block 110 is secured to each sideplate 38, and clamping 7 plates 112 fixed to holder 100 are tightenedagainst support blocks 110 by screws 114 to positively retain holder inthe selected positions of adjustment, it being understood that clearanceslots 116 are provided in blocks to allow the holder 100 to moverelative thereto. Should it be desired to always include substantiallythe same type of long fibers in the end product, the aforementionedadjustment means 98 may become unnecessary.

The long fiber material 62 is presented to the teeth of the rapidlyrotating lickerin 92 at approximately 11 oclock position, and thelickerin teeth comb out and individualize the long fibers as the teethmove past the nose bar 102.

In order to be abe to vary and control the mixing characteristics of thelong and short fibers as their individual carrier streams are combined,as will hereinafter appear, the width of the throat of the mixing zone25, i.e., the distance between the fiberizing means 24 and 26, can bevaried, and adjustment means 118 is provided for moving lickerin 92 inand out in a horizontal plane. The axle 122 of lickerin 92 is mounted inslide members 124 that ride in horizontal slots in side plates 38, andadjustment means 1 18 is provided by adjusting screws 126 that arethreaded into slide members 124 for varying the position of lickerin 92.Adjusting screws 126 react against plates 128 that are secured to sideplates 38.

Lickerin 92 is rotated in a clockwise direction, as shown by thedirectional arrow in FIG. 3, and to this end, the output shaft 132(FIG. 1) of a motor is connected to lickerin 92 by a belt drive systemincluding a sheave 134 on shaft 132, a sheave 136 on axle 122, and anendless belt 138 trained over sheaves 134 and 136. Motor 132 can bebolted to an upright 30 of a main frame, as illustrated, or it can bemounted on the floor, and the motor mounting means may be adjustable, sothat the position of the motor 130 can be changed when theposition ofthe lickerin 92 is changed. Motor 130 rotates lickerin 92 at a highspeed that allows the teeth 96 to comb out and individualize the longfibers from supply 62 at a rapid rate, and for purposes of illustration,a rotational speed of 2,400 rpm has been found to be satisfactory toproduce a desired quantity of individualized rayon fibers from pickerlap fiber source without damage to the fibers. Lickerin 92 can berotated at higher speeds for greater throughput, if desired.

The rotation of lickerin 92 generates a stream of gas, e.g., air, asindicated by the directional arrow 139 in FIG. 3, that flows under thenose bar assembly 68, to initiate a fiber doffing action, in cooperationwith the centrifugal forces acting on the fibers, substantiallyimmediately after the fibers are combed from source 62. Since doffing isinitiated substantially immediately following fiber individualization,i.e. at about the 12 O- clock position, a large number of the fibers aregiven an initial trajectory having a significant component of motiontoward the oncoming fibers from fiberizing means 26. As the fibers areaccelerated and entrained in the stream 139 they possess substantialkinetic energy because of their mass and velocity, and the inertia ofthe fibers tends to keep them moving along a path generally in thedirection of their initial trajectory.

A further gas stresm, represented by the directional arrow 140 in FIG.3, flows generally vertically downwardly through the mixing zone 25toward the fiber collecting means 28 adjacent the periphery of lickerin92, and any undoffed fibers are removed from the lickerins by the stream140. Stream 140 serves as a common carrier stream for the fibers doffedfrom both lickerins as will hereinafter appear. The gas stream 140 canbe generated in part from a separate source 142, such as a commerciallyavailable air knife, or the gas stream can be generated by the combinedaction of the separate carrier streams and the suction actuatedcondenser means 28, as will hereinafter be explained. In any event, thecommon stream 140 receives the oncoming fibers and partially, but notcompletely (as will hereafter appear), overcomes their inertia to changetheir trajectory and direct them to the condensing means 28.

In the event that an air knife is used, adjustment means 144 (FIG. 1)may be provided for positioning the air knife in an optimum positionrelative to the mixing zone 25 to get the desired type ofdirectionalized air flow. Adjustment means 144 is arranged to move theair knife 142 both vertically and angularly, if desired. To this end,the air knife 42 includes laterally extending support portions 146 ateach end thereof having internally threaded vertically extendingopenings therein. Frame members 148 are secured to side plates 38, andadjusting screws 150 adjacent each side plate 38 extend through thethreaded openings in support portions 146 and through aligned bores inframe members 148 so that the air knife 142 can be vertically adjusted.A worm wheel 152 is provided at each end of air knife 142, and angularadjustment of the air knife is accomplished by worm gears 154 onadjusting screws 156 that are mounted for horizontal movement inhorizontal bores in frame members 148. By appropriate adjustment ofadjusting screws 150 and 156 the direction of the air stream emanatingfrom the orifice at the lower end of the air knife can be varied andcontrolled.

A mass of short fibers 162, such as pulpboard or linters board in sheetform, is fed to fiberizing means 26 by a cylindrical feed roll 164,which is positively rotated by conventional means, not shown, to controlthe rate and amount of short fiber material that is fed to thefiberizing means 26. The opposite ends of feed roll 164 are rotatablymounted in support arms 166 that are pivotally connected between sideplates 38 by pivot members 167. Feed roll 164 is biased towards a nosebar assembly 168 by springs 169 that bear against support arms 166, andsprings 169 urge the support arms in a counterclockwise direction aboutpivots 167. Springs 169 react between support arms 166 and a nut 170 onspring retention members 172 that are pivotally connected to side plates138, it being understood that the members 172 pass through clearanceopenings in the support arms 166. Spring holding members 172 include astop surface 174 for limiting the pivotal movement of the support arms166, thereby establishing a minimum clearance between the mass 162 ofshort fibers and the nose bar assembly 168.

A material opening cylinder 176 is mounted for rotation in acounterclockwise direction between side plates 38 below feed roll 164,and opening cylinder 176 preferably takes the form of a lickerin havingspirally wound toothed clothing 178 thereon. As is evident from FIGS. 1and 3, lickerins 92 and 176 are positioned in parallelism with oneanother and are preferably of the same diameter. In an exemplaryembodiment of the invention, lickerins 92 and 176 have an outer diameterof approximately 9 a and a length of approximately 40 inches. Theindividual teeth 180 of clothing 178 are selected to optimize theopening or grinding conditions for the short fiber material 162. Thepitch and height of the teeth used on the lickerin for the pulpboard mayvary, good results being obtained with a tooth pitch or about threethirty-second inch to about one-half inch and a tooth height of aboutthree thirty-second inch to about one-half inch. The rake angle of theindividual teeth 180 of clothing 176 is selected to give the optimumopening characteristics for the specific material being fed to thelickerin. The angle of the teeth of the lickerin for the pulpboard mayalso vary, generally within the limits of about l0 to about +10. Tofacilitate doffing the teeth may preferably have a negative rake.

Optimum conditions for substantially completely opening the short fibermaterial 162 may be further established by virtue of an adjustment means182 which varies the position of the nose bar assembly 168 relative tothe lickerin 176. The nose bar assembly 168 includes a holder 184 havinga nose bar 186 at the lower end thereof that faces feed roll 164. Thenose bar 186 preferably has a straight or flat material engaging surfacefor supporting the short fiber pulp material 162 in position to have thematerial combed and the fibers individualized by lickerin 176. Plates188 (FIG. 1) are secured to opposite ends of the holder 184, and plates188 are generally T-shaped in cross section, with the offset portion ofeach plate 188 riding in an inclined slot 190 in one side plate 38. Theadjustment means 182 is provided by adjusting screws 192 that arethreaded into openings in plates 188, with the screws 192 reactingagainst saddle members 194 that are fixed to the side plates 38. Plates188 include a plurlaity of elongate slots 196 (FIG. 1) therein, andclamping bolts 198 that are threaded into side plates 38 impale slots196, it being understood that the bolts 198 are tightened to positivelyretain the holder 184 in the selected position of adjustment relative tolickerin 176.

The nose bar holder 184 can also be adjusted angularly relative to thefeed roll 164 and the teeth on lickerin 176, and to this end, a block200 on one side of the holder 184 is pivotally mounted on a shaft 202that the extends transversely between plates 188. Further clampingplates 204 are affixed to the ends of shaft 202, and arcuate slots 206in clamping plates 204 are impaled by clamping bolts 198, that aretightened to positively retain the holder 184 in the selected positionof angular adjustment. lf should be understood that the adjustment meansfor either or both of the nose bar assemblies is not critical to theprocess of the present invention, and fixed lickerin-nose barrelationships may be established for both supplies of fibers,particularly if each lickerin and nose bar is to always open materialhaving substantially the same characteristics, but the adjustabilityfeature adds flexibility to the machine making capable of use withmaterials having different characteristics.

As is mentioned briefly above in connection with lickerin 92 apreselected spacing between the lickerins 92 and 176 can be establishedby virtue of an adjustment means 210 for varying the position oflickerin 176 relative to the mixing zone and lickerin 92 acting incombination with the adjustment means 118 for lickerin 92. To this end,the axle 212 of lickerin 176 is mounted in slide members 214 that ridein horizontal slots 216 in side plates 38. Lickerin 176 is moved in andout by adjusting screws 218 that are threaded into slide members 214,with screws 218 reacting against plates 220 that are secured to the sideplates 38. By virtue of the adjustment means 118 and 210, the width ofthe throat portion of the mixing zone 25 between the lickerins 92 and176 can be varied and controlled. The distance between the lickerinswill, to a certain extent, be determinative of the volume of fibers thatare entrained in gas stream 140 and ultimately deposited upon receivingmeans 28. A spacing of approximately .25 inches has been found to giveexcellent results although smaller gaps, and larger gaps up to 1.5inches have also given satisfactory results.

Lickerin 176 is rotated in a counterclockwise direction, as shown by thedirectional arrow in FIG. 3, and to this end, the output shaft 222(FIG. 1) of a motor 224 is connected to lickerin 176 by a belt drivesystem including a sheave 226 on shaft 222, a sheave 228 on axle 212,and an endless belt 230 trained over sheaves 226 and 228. Lickerin 176may be rotated at a speed substantially faster than the rotational speedof lickerin 92 when lickerin 176 is opening short fiber material andlickerin 92 is opening long fiber material. For purposes ofexample, arotational speed of 4,000 rpm has been found satisfactory to produce adesired quantity of high quality individualized pulp fibers from a pulpboard. Faster rotational speeds for lickerin 175 can be used if greaterthroughput is desired. Like motor 130, motor 224 is illustrated as beingsecured to an upright of the main frame, although it may be mounted onthe floor, and the mounting for motor 224 may also be adjustable.

In order to improve the opening action of lickerins, an arcuate coverplate 233 (shown only for lickerin 92) may be positioned over theportion of the lickerin between the nose bar and the upper end of themixing zone. The end of cover plate 233 is spaced from the nose bar 102,so that the rotation of the lickerin 92 will draw in a stream of gas,e.g. air, between the cover plate 233 and nose bar 102 that will forcethe fibers against the lickerin 92, while at the same time force thefibers cooling the cover plate and helping to convey fibers. A gap ofone-half inch between the cover plate 233and nose bar 102 has proven tobe effective in providing a stream that forces the upper layer of fibersinto the teeth of lickerin 92 for additional working.

Because of the relatively high rotational speeds of lickerins 92 and176, each lickerin creates a zone of gas, e.g. air, movingcircumferentially therearound. As is mentioned above, lickerin 92generates gas stream 139 that initiates doffing of the individualizedfibers from lickerin 92. Likewise, lickerin 176 generates a gas stream,represented by directional arrow 231, that passes under nose barassembly 168 and in conjunction with centrifugal force and toothconfiguration initiates a fiber doffing action substantially immediatelyafter the fibers have been combed from source 162. As is evident fromFIG. 3, the short fiber material is presented to the teeth on lickerin175 at approximately a l oclock position. Since a large number of thefibers are doffed from lickerin 176 substantially immediately followingindividualization, i.e. at about a 12 oclock position, the fibers aregiven an initial trajectory having a significant component of motiontoward the oncoming fibers from lickerin 92. As the fibers areaccelerated into stream 231, because of their inertia, they will tend tocontinue to move in their initial direction.

Since the lickerins 92 and 176 are rotating in opposite directions, thezones of air generated thereby cooperate to produce at least a portionof the common high speed stream that is directed downwardly between thelickerins through the mixing zone 25 toward the fiber receiving means28. It is has been found that with rotational speeds of theaforementioned magnitude, i.e., 2,400 rpm for lickerin 92 and 4,000 rpmfor lickerin 176, and with the tooth-to-tooth spacing of the lickerinsbeing inthe aforementioned range, the lickerins can produce asubstantial portion of the velocity of stream 140, depending of courseon the presence or absence of air knife 142 and the magnitude of thesuction drawn by fiber receiving means 28.

It has been found that at the lickerin rotational speeds mentioned aboveand with condensing means 28 pulling approximately 400 cfm, the combinedair stream 140 has an average volumetric flow rate of approximately 500cfm. This flow rate gives the individual streams 139 and 231 and thecommon stream 140 sufficient velocity to effect the desired fiberdoffing and blending, so that a separate gas source, such as air knife142 is not necessary.

As has been mentioned above, the fibers entrained in gaseous streams 139and 231 posess substantial kinetic energy, and their inertia tends tokeep them moving in the initial doffing direction. As the separategaseous streams 139 and 231 merge into the common gaseous stream 180,the combined forces of gravity and the suction applied by the fiberreceiving means tend to cause the fibers to assume a more downwardtrajectory, but the momentum of thefibers is such that as the streams139 and 231 are impelled against one another, a substantial portion ofthe long and short fibers become intermixed. The position at which thestreams 139 and 231 are brought together, and the degree of blending ofthe long and short fibres can be controlled by varying certain machineparameters such as the volume and/or velocity of gas flowing through themachine, the speed of the lickerins, the rate of fiber input, thegeometry of the ducting system, and the position of the fiber receivingmeans.

In one mode of operation, at relatively low gas volumes, in forming aweb of blended long and short fibers, since lickerin 178 is rotating ata substantially greater speed than lickerin 92, a zone of lower pressureis created in the common high speed stream 140 in mixing zone 25 betweenand below the lickerins 92 and 176. The individualized long fibers fromthe lickerin 92 are accelerated toward the zone of low pressure andretained substantially under tension until the fibers are deposited uponthe fiber receiving means 28. The drawing of the long fibers into thezone of low pressure and the aforementioned inertial impelling of thefibers together, cause the long and short fibres to be homogeneouslyblended in the mixing zone 25.

Also, as is explained in detail in the commonly assigned, concurrentlyfiled application Ser. No. 108,545 of A. Farrington, the geometry of theducting of the machine, may be configured to insure that the gaseousstreams will have turbulent flow characteristics from the point ofdoffing to the point of deposit of the fibers. This, together with theinterposition ofa baffle between the separate gaseous streams can resultin the production of various different webs, including a web comprisedof homogeneously blended long and short fibers. Furthermore, as isexplained in the commonly assigned, concurrently filed Ruffo et al.application Ser. No. 108,546, at increased gas-to-fiber volume ratios,various high quality webs can be produced at high production rates.

The lower portion of the mixing zone 25, i.e., the portion between thelickerins 92 and 176 and the fiber receiving means 28 is preferablyclosed by deflector plates 232 and 234 that are secured between sideplates 38. Because the lower portion of the mixing zone 25 is wider thanthe throat portion between the lickerins 92 and 176, the stream 140having the intimate admixture of long and short fibers therein tends todecelerate as it approaches the fiber receiving means 28, and hence itis desirable that the fiber receiving means 28 be positionedsufficiently closely to the lickerins 92 and 176 that deceleration ofthe rayon fibers in the stream is minimized. While the receiving means28 is illustrated substantially immediately below lickerins 92 and 176in FIG. 3, the present invention does not require that the fiberreceiving means be positioned this close to the lickerins, andsatisfactory webs have been produced withh the distance between thecenter line to center line spacing between the lickerins and receivingmeans being as much as 16 inches.

The fiber receiving means 28 is defined by a suction actuated fibercondensing drum 236 having a foraminous fiber supporting surface formedby a radially open honeycomb network 238 (FIG. 3) that has at least onefine mesch screen 240 thereover. In an exemplary embodiment of theinvention, drum 236 has an outer diameter of approximately 12 inches.Drum 236 is rotated (clockwise in the illustrated embodiment asindicated by the directional arrow in FIG. 3) by a motor 242 through achain drive (FIG. 1) including a sprocket 244 fixed to the output shaft246 of the motor 242, a sprocket 248 fixed to the drum 236, and anendless chain 250. The fiber receiving means 28 further includes astationary central portion 252 having flanges 254 that extend radiallyoutwardly into sealing engagement with the drum 236. In the embodimentof FIGS. 1-3, one flange 254 is positioned in substantial alignment withdeflector plate 232, while the other flange 254 is circumferentiallybeyond deflector plate 234. A conduit 256 (FIG. 2) is connected tostationary portion 252 and to a suitable source of negative pressure forapplying a suction to drum 236 between the flanges 254. It will beappreciated that the suction of the fiber receiving means 28 cooperateswith the air streams created by the oppositely rotating lickerins 92 and176 to provide a pressure gradient across the mixing zone 25 which drawsthe individualized and homogeneously blended long and short fibers ontothe drum 236 to build a web. The stream 140 that is produced by theconjoint action oflickerins 92 and 176 and the negative pressure of thefiber receiving means 28 is retained at a large enough velocity that asufficient means interstitial spacing between the fibers is maintainedin the mixing zone which allows the fibers to remain intermixed withoutagglomeration prior to deposition on the fiber receiving means.

In a typical example of the practice of the invention disclosed herein,lickerins 92 and 176 of the size set forth above were rotated at theabove mentioned speeds, and 555 pounds of fibers per hour were fed tothe lickerins, with percent of the fibers being pulp fibers, and 25percent of the fibers being rayon fibers. The tooth-to-tooth spacingbetween the lickerins was 0.25 inches, and deflector plates 232 and 234were parallel with one another and spaced by .625 inches. The air streamhad an average volumetric flow rate of 500 cubic feet per minute (2,250pounds per hour), and there was a feed ratio of about 4.05 pounds of airper pound of fiber. The average volume ratio of air to fiber wasapproximately 5,000 to l. Pitot readings were taken at various positionsbetween deflector plates 232 and 234, and these readings indicated thatstream 140 had a high velocity zone adjacent deflector plate 234. Visualobservations confirmed that a large number of fibers were entrained inthe high velocity portion stream 140, and that a majority of the fiberswere condensed on the screen adjacent deflector plate 234. With theconveyor 29 operating at a web take away speed of 200 feet per minute,it was found that an extremely satisfactory web W was produced having anaverage weight of about 900 grains per square yard.

It will be understood, of course, that conveyor 29 is intended totransport the web W to a further processing zone, such as a bonding zonewhere a bonding agent may be applied to the web.

The nonwoven webs obtained by the process of the present invention maybe post-treated by any suitable conventional technique, to bond the weband provide the required strength and coherency characteristics for agiven product. The particular type of bonding technique chosen willdepend on various factors wellknown to those skilled in the art, e.g.,the type of fibers, the particular use of the products, etc. To thisend, typical of the conventional techinques are web saturation bonding,suction bonding, foam bonding, print bonding, fiber bonding, fiberinterlocking, spring bonding, solvent bonding, scrim bonding, viscosebonding, mercerization, etc.

In the case of web saturation bonding, the nonwoven web is generallysoaked with a solution or emulsionbinder, and thereafter, the excessfluid is removed usually by mechanical means (e.g. squeeze rollersand/or vacuum), followed by evaporation. In the case of suction bonding,a web is treated with a suitable binder by soaking and the excessremoved by means ofa vacuum apparatus. In foam bonding, which is avariation of saturation bonding and is particularly useful for productsrequiring good bulk and through-bonding, a foam binder is employed. Inprint bonding, generally employed where softness and absorbency isrequired, a bonding agent will be printed onto the web by, e.g. gravuretype rolls. The web can be wet or dry when printed and generally thebinder is a water, solvent or plastisol based one.

In fiber bonding techniques, employed where a percentage of the fibersin the web are semi-soluble in certain solvents, e.g. hot water, the webmay be bonded by adhesive or by treating the web with a suitable solvente.g. polyvinyl alcohol. In a variation of this procedure, if the webincludes thermoplastic fibers such as polypropylene, VINYON or lowmelting polyester, hot roll embossing calendars may be employed. Stillfurther, 'in other case, a low melting spun bonded web may be placedbetween higher melting fiber webs and hot calendered. Thermoplasticpowders may also be used in this technique.

In the case of mechanical interlocking bonding techniques, needle loomsare employed in bonding soft fiber webs. Boards of needles with barbsdownwardly pointed perforate the web and entangle the layers. Avariation of this type of bonding technique is stitch bonding with yarn,as may be accomplished by using an ARACHNE apparatus or with the fibersof the web itself.

As the name implies, spray bonding techniques spray a binder onto theweb which is subsequently passed into a drying chamber. This type ofbonding is particularly useful where high loft is required in products,e.g. which are suitable for use as air filters. Solvent bonding employsa solvent which is applied to the web to soften the fiber surface andrender it adhesive. Typical solvent bonding employs the use of chloralhydrate of DMSO (dimethylsulfoxide).

ln scrim bonding, a scrim layer or yarn layer act as carriers for a wetor thermoplastic adhesive used to laminate the nonwoven webs to one ormore layers of a substrate, e.g. tissue. In viscose bonding, which is aspecial case of print or saturation bonding, cellulose xanthate isregenerated to pure cellulose on the inner sections of the fibersforming the nonwoven web. in a like manner, acid solutions of nylon maybe regenerated in situ.

in mercerization bonding techniques, nonwoven webs are bonded using theuncurling manner of caustic solutions, e.g. caustic soda on all-cottonnonwoven webs. The fibers unwind to entangle each other and, thereafter,the resulting product is thoroughly washed.

The above list of bonding techniques is not intended to be exhaustive asothers known to those skilled in the art may be employed, e.g. bondingwith the use of high pressure streams of water or other fluids directedonto the nonwoven web to cause the fibers to interlace; or stillfurther, using ultrasonic waves and laser beams.

in any of the above dry bonding techniques, the binder areas may be ofany suitable shape and size and may be continuous or discontinuousstraight, sinuous, curved, or wavy lines; rows of polygons, circles,annuli, or other regular or irregularly shaped geometric figures; all ofwhich normally extend across the width of the nonwoven fabric at variousangles to the long direc tion thereof. Specific examples of such binderareas are noted in US. Pats. Nos. 2,705,688, 2,705,687, 2,705,498 and3,009,822.

The amount of binder employed will depend on the type of bondingtechnique used and depend on the type and quality of product desiredi.e. the amount of binder add-on to the nonwoven web maybe variedaccording to the technique employed and will vary within relatively wideranges, depending to a large extent upon the intended use of thenonwoven fabric, upon its type, weight and thickness, as well as uponthe specific binder employed. Typically, the binder areas should notexceed a substantial amount of the total surface of the nonwoven fabric,if a soft hand, drape and other textile-like properties andcharacteristics are desired or required. in cases where a somewhatdifferent hand and drape is acceptable, increased binder coverages of upto almost any value, say 50 percent or even 75 percent, are useful. Forsome binders, as low as from about 2 percent to about 20 percent byweight has been found sufficient; for others, as high as from about 40percent to about percent or more by weight has been found preferable.Within the more commercial aspects of the present invention, however,binder add-ons of from about 3 percent to about 40 percent by weight areknown in the art to be satisfactory.

The particular type of binder used may be selected from a large group ofbinders now known in the industry for such purposes. Non-migratorybinders, such as hydroxyethyl cellulose and regenerated cellulose, arepreferred inasmuch as they yield sharp and clear boundaries of bondedareas and unbonded areas. Water-insoluble or water-insensitive binders,such as melamine-formal-dehyde, urea formaldehyde, or the acrylicresins, notably the self-cross-linking acrylic ester resin, are alsopreferred inasmuch as they are capable of completely resisting asubsequent aqueous reararanging treatment. Other binders, however, arealso of use and would include polyvinyl acetate, polyvinyl chloride,copolymers thereof, polyvinyl acrylate, acrylate, polyethylmethacrylate, polyvinyl butyral, cellulose acetate, ethyl cellulose,carboxymethyl cellulose, etc.

Following bonding, the nonwoven webs may be treated again according toconventional procedures for any further desired purpose, such as fordecorative reasons.

Still further, the nonwoven webs may be treated with various types ofresinous coatings according to conventional techniques, or alternativelyby bonding the nonwoven web to various substrates to provide laminates.

The products obtained by the process of the present invention, followingbonding, find use in various and diverse fields. Moreover, the randomnonwoven webs will now have greater utility because of their greateravailability, and may be used to replace oriented nonwoven webs whereimproved machine and cross direction strength ratios are required.Typical of the uses to which the products can be put includelimited-wear garments such as dresses, medical and industrial apparel,caps, hospital uses such as for surgical products, e.g. bandages,alcohol preparation, towelling, surgical pad covers, sanitary productssuch as napkins, absorbent products such as diapers and diaper facings,polishing and buffing cloths, wash cloths, wiping cloths, etc., consumerproducts such as table cloths and place mats, serviettes, book jackets,labels and tags, mop covers, cosmetic pads, filtration uses such as airfiltration media as well as liquid filtration media in the chemical andfood industries, etc. This is not exhaustive and many different uses arewell known to those skilled in the art.

lt should also be understood that while the persons and apparatus of thepresent invention have been described in terms of producing a web thathas at least a portion that consists of homogeneously blended long andshort fibers, the present invention comprehends that the web may beformed entirely either of short fibers or long fibers. Furthermore,while adjustment means have been illustrated for varying the positionsof the lickerins, the nose bars, the fiber receiving means, and the feedrolls, these mechanisms may also be positioned at fixed locations, onthe frame in instances where the apparatus will continuously beoperating upon fibrous materials having the same characteristics.

Also, the web formation characteristics and the dry strength of theresulting web can be improved by selecting both machine and fibermaterials which produce an appropriate electrostatic attraction and/orrepulsion of one fiber to another and their relationship to the machineitself. During transport of the fibers through the mixing zone to thecondensing screen, it is desirable to maintain the voltages between thefibers to reduce coalescence. This can be accomplished by selectingfibers and machine components that produce fibers with like charges soas to eletrostatically repel one another when they are transported inthe common air stream. In some instances, to optimize the buildup of webW on the condensing screen, fibers can be chosen that will beelectrostatically attracted to one another, and this phenomenon can beespecially important in retaining the air laid web as a unitary massduring transport from the condensing screen to a further processingstation wherein a binder is applied to the web. It is also a factor inhow the fibers line up relative to one another.

Instead of merely having outwardly diverging deflector plates, such as232 and 234, at the lower end of the mixing zone 25, many differentarrangements can be utilized, and several of these are illustrated inFIGS. 4-12. It will be understood that with the various arrangementsillustrated in FIGS. 4-12, the air flow patterns at the lower end of themixing zone can be modified to control the manner in which the airbornefibers are accumulated on drum 236. While several different arragementshave been illustrated, these arrangements have been selected for purposeof example only, and in no way should they be construed as limiting theinvention as defined in the appended claims.

In the embodiment of FIG. 4, deflector plates 260 and 261 at the lowerend of the mixing zone 25 are arranged so that the intermediate portionof the mixing zone is a narrow channel. Deflector plate 261 may haverounded portions 261a and 26lb at the upper and lower ends thereof,respectively, to guide the large number of fibers traveling in the highvelocity portion of stream 140, assuming that low gas volumes areflowing through the machine, as described above. A sealing roll 262 iscarried upon an arm 263 that is pivotally mounted to the frame of themachine, and sealing roll 262 is driven by conventional means, notshown, with the sealing roll being positioned in alignment with oneflange 254 of the internal portion 252 of drum 236. A baffle 264 ispositioned below deflector plate 260, and includes an inclined portion265 that extends tangentially with respect to the periphery of drum 236.An extension plate 267 is pivotally connected to the lower end ofdeflector plate 260, and the lower end of plate 267 is spaced from theperiphery of drum 236 between the flanges 254.

With the arrangement of FIG. 4, the fibers are deposited on drum 236essentially between roll 262 and plate 267, with the fibers being guidedaround the rounded portion 26lb of deflector plate 261. A generallytriangularly shaped blocking element B may be positioned above lickerins96 and 176 to prevent any dense particles that are thrown off thelickerins by centrifugal force from entering the mixing zone. The denseparticles collected on blocking element B preferably are continuouslyremoved from the machine by means, not shown, such as an air stream, ora screw conveyor or other means.

In many instances it is desired to concentrate the highest portion ofthe suction from the condensing means over a relatively narrow area inthe fiber accumulating zone, and several arrangements for accomplishingthis are illustrated in FIGS. 5-9. In the embodiment of FIG. 5, theinternal portion 252 of the fiber receiving means is angularlyadjustable, and the sealing flanges 254 are spaced apart by an angleslightly in excess of A pair of flanges 266 extend inwardly of theinternal portion 252 of drum 236, and baffles 267 are fixed thereto.Baffles 267 includes parallel portions 268 that extend verticallyupwards toward the mixing zone, so that the fibers are deposited on thedrum 236 in a relatively narrow area with high velocity as determined bythe distance between the baffle portions 268. The thus laid fibers areretained on the screen by the low velocity and low suction areasoutwardly of baffle portions 268 to firmly hold the web on the screen asit moves out of the fiber condensing zone. The lower portion of themixing zone 25 in the embodiment of FIG. 5 includes deflector plates 260and 261 similar to those illustrated in FIG. 4; and a plate 267a,similar to plate 267 in FIG. 4, is pivotally connected to the lower endof deflector plate 260, with plate 267a extending vertically downwardlyinto engagement with drum 236. As is evident from FIG. 5, the internalbaffles 268 on drum 236 are positioned in alignment with plate 267a andsealing roll 262. With the arrangement of FIG. 5, even though thesealing flanges 254 on drum 236 may be positioned more than 90 from oneanother, the fibers are deposited on the drum in an extremely narrowzone determined by the spacing between baffles 268.

In the embodiment of FIGS. 6 and 7, the sealing flanges 254 of thecondensing drum 236 are positioned relatively closely to one another,and a narrow area of suction application is obtained by a straightbaffle member 271 that is positioned in close proximity to one of thesealing flanges 254. In the embodiment of FIG. 6, a stationary tube 272extends transversely across the frame of the machine below deflectorplate 260, and in alignment with one sealing flange 254. In thearrangement of FIG 7, the condensing drum 236 is offset laterally (tothe left) relative to lickerins 92 and 176. A plate 273 is pivotallyconnected to the lower end of deflector plate 260, and bears against theperiphery of drum 236 in alignment with one flange 254, while sealingroll 262 is positioned in alignment with the other flange 254. As isevident from FIG 6, the internal baffle 271 on drum 236 is substantiallyparallel to the deflector plates 260 and 261, while in the embodiment ofFIG. 7, the baffle 271 is positioned at an angle with respect to thedeflector plates 260 and 261.

In the embodiment of FIG. 8, like the embodiment of FIG. 7, thecondensing drum 236 is offset to the left relative to the verticalcenter line of the mixing zone. De-

1. Web forming apparatus for forming a nonwoven web of fibers from at least two sources of fibers, one of said sources being a source of at least partially pre-opened textile length fibers and the other of said sources being a source of short fibers, said apparatus comprising: a pair of lickerins, one having a different tooth profile than the other; means rotatably mounting said lickerins in spaced parallel relationship, said one lickerin being located adjacent the source of textile length fibers and said other lickerin being located adjacent the source of short fibers, and the converging facing surfaces of said lickerins downstream of said fiber sources defining a first portion of a duct means that is funnel shaped in cross section and which communicates with said sources of fibers, said duct means having a second portion below the center lines of said lickerins, communicating with said first portion for carrying fibers to a fiber deposition zone; means for rotating said one lickerin in a given direction and at a given speed; means for rotating said other lickerin in an opposite direction and at a greater speed than said one lickerin; means for guiding each source of fibers into contact with its respective lickerin at a location thereon at which the tangential velocity of said lickerins has a component toward one another whereby each lickerin individualizes fibers from its respective source; fiber collecting means communicating with the second portion of the duct means and including a movable foraminous member at said depositing zone to collect said fibers and form a web of nonwoven fibers, And means for applying a suction to said foraminous member for providing separate gaseous streams flowing along a path extending about the periphery of said lickerins for a major portion of the distance between said contact location and through the first portion of said duct means to (a) doff at least some of the individualized fibers from each lickerin, (b) entrain the individualized fibers in their respective gaseous streams, and (c) convey said entrained fibers in said separate gaseous streams through said duct means along flow paths at least initially directed toward one another, said duct means guiding said gaseous streams whereby at least a portion of said gaseous streams are combined to intermix at least a portion of the fibers in one gaseous stream with at least a portion of the fibers in the other gaseous stream after which said blended fibers are collected on said foraminous member.
 2. Web forming apparatus as set forth in claim 1 in which each fiber source guiding means includes a material supporting surface adjacent each source of fibers, each lickerin-supporting surface relationship being selected to establish optimum conditions for substantially completely opening said textile fiber and short fiber materials.
 3. Web forming apparatus as set forth in claim 2 including means for adjusting the relative location of each lickerin and its supporting surface.
 4. Web forming apparatus as set forth in claim 1 wherein the second portion of said duct means is defined by a deflector plate mounted beneath each lickerin, each deflector plate having an upper end positioned adjacent one lickerin and a lower end positioned adjacent the fiber collecting means.
 5. Web forming apparatus as set forth in claim 1 including means for adjusting the position of said foraminous member relative to said lickerins.
 6. Web forming apparatus as set forth in claim 5 wherein said means for adjusting said foraminous member incudes means for varying the position of said suction applying means relative to said fiber receiving station.
 7. Web forming apparatus as set forth in claim 1 wherein said lickerins are spaced closely to one another to form a narrow gap therebetween.
 8. Web forming apparatus as set forth in claim 1 wherein said foraminous member is positioned generally centrally below said lickerins. 